Organic extraction

Fig- 23(F) shows a similar distillation assembly for isolating a pure liquid which is present in an organic extract and which may finally require fractional... 

Solvent extraction is a relatively high cost process, owing to the specialty organic extractants required and the expenses of recovery and storage of... 

Ce(IV) extracts more readily iato organic solvents than do the trivalent Ln(III) ions providing a route to 99% and higher purity cerium compounds. Any Ce(III) content of mixed lanthanide aqueous systems can be oxidi2ed to Ce(IV) and the resultiag solutioa, eg, of nitrates, contacted with an organic extractant such as tributyl phosphate dissolved in kerosene. The Ce(IV) preferentially transfers into the organic phase. In a separate step the cerium can be recovered by reduction to Ce(III) followed by extraction back into the aqueous phase. Cerium is then precipitated and calcined to produce the oxide. 

A solution of 6.3 g (0.9 moles) ethoxyacetylene in 50 ml ether is added dropwise during 30 min to a Grignard reagent prepared from 2.18 g (90 mg-atoms) magnesium and 9.81 g (90 mmoles) ethyl bromide. The reaction mixture is stirred for 1 hr at room temperature and then a solution of 3 g (9 mmoles) 3) -acetoxyandrost-5-en-I7-one in 50 ml dry ether is added dropwise. The mixture is refluxed for 1 hr and after cooling to 0° poured into 100 ml of an aqueous ammonium chloride solution. The aqueous solution is extracted with ether, and the organic extract is washed with ammonium chloride solution and water, dried, and evaporated. The residue is chromatographed on 130 g alumina (activity III). Elution with petroleum ether-benzene (1 1) yields, after crystallization from acetone-hexane, 1.27 g (35%) 3j5-acetoxy-17a-ethoxyethynylandrost-5-en-17) -ol mp 138-139° Ho -122°. 

A total of 3 g (0.13 moles) of sodium hydride is added to a solution consisting of 10 g of 17 -hydroxy-5a-androstan-3-one (36 mmoles) in 200 ml of benzene and 10 ml of ethyl formate. The reaction mixture is allowed to stand under nitrogen for 3 days followed by dropwise addition of 10 ml of methanol to decompose the excess of sodium hydride. The solution is then diluted with 300 ml water and the layers are separated. The basic aqueous solution is extracted with ether to remove neutral material. The aqueous layer is acidified with 80 ml of 3 A hydrochloric acid and the hydroxymethylene steroid is extracted with benzene and ether. The combined organic extracts are washed with water and saturated sodium chloride solution and then dried over magnesium sulfate and concentrated. The residue, a reddish-yellow oil, crystallized from 10 ml of ether to yield 9.12 g (83%) of 17 -hydroxy-2-hydroxymethylene-5a-androstan-3-one mp 162-162.5°. Recrystallization from chloroform-ether gives an analytical sample mp 165-165.5° [a]o 53° (ethanol) 2 ° 252 mjj. (g 11,500), 307 m u (e 5,800). 

FIGURE 5.19 N-Tertninal analysis using Edman s reagent, phenylisothiocyanate. Phenylisothiocyanate combines with the N-terminus of a peptide under mildly alkaline conditions to form a phenylthiocarbamoyl substitution. Upon treatment with TFA (trifluo-roacetic acid), this cyclizes to release the N-terminal amino acid residue as a thiazolinone derivative, but the other peptide bonds are not hydrolyzed. Organic extraction and treatment with aqueous acid yield the N-terminal amino acid as a phenylthiohydantoin (PTH) derivative. 

A mixture of a-naphthol 41 (15.0 g, 0.1 mol), phenylhydrazine 42 (11.0 g, 0.1 mol) and sodium bisulfite solution (36 %, 250 g) was heated at reflux for 15 h. A further 4 g of phenylhydrazine was added and heating continued for 15 h, after which time the majority of the a-naphthol was consumed. After cooling, the mixture was extracted with ether. The oily, ether and aqueous insoluble residue was warmed with cone. HCl until a dark crystalline mass developed. After cooling, the mixture was extracted with ether. The organic extract was dried and concentrated to afford a crystalline residue which was purified by recrystallisation from ethanol to afford the product 43 as a white crystalline solid, mp 225 °C. A reaction yield is not given. 

To a solution of dihydronaphthalene 41 (250 mg, 0.77 mmol) in CH2CI2 (5 mL) was added methyl trifluoromethanesulfonate (227 mg, 1.38 mmol). The mixture was stirred at rt until the starting material had been completely consumed as judged by TLC analysis (3 h). The mixture was cooled to 0°C and a solution of NaBHt (111 mg, 2.92 mmol) in 4 1 MeOH THF (3 mL) was slowly added. The mixture was warmed to rt then quenched with saturated aqueous ammonium chloride (50 mL). The resulting mixture was extracted with CH2CI2 (3 X 50 mL) and the combined organic extracts were dried over anhydrous sodium sulfate, filtered, and concentrated in vacuo. The resulting material was dissolved in 4 1 THF/H2O (5 mL) and oxalic acid (485 mg, 3.85 mmol) was added. The reaction... 

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